The disclosure relates generally to identification of biological samples, and more particularly, to the use of a radio frequency identification system for identifying containers which may contain biological samples therein.
Radio frequency identification, or RFID, is a generic term for technologies that use radio waves to identify objects, such as, e.g., containers for biological samples. RFID tags may store a series number or other identifier that identifies the container or the contents thereof, on a microchip attached to an antenna. Collectively, the microchip and antenna are referred to as an RFID tag or RFID transponder.
RFID tags can be categorized as active, semi-passive, and passive RFID tags, which can be distinguished from one another on the basis of power supply. Passive RFID tags are battery-free, and react to a specific, reader-produced inductively coupled or radiated electromagnetic field by delivering a data modulated RF response. Passive RFID tags draw power from the reader, which emits electromagnetic waves that induce a current in the antenna of the RFID tag. The voltage generated may be stored in a capacitor in the RFID tag. The RFID tag then transmits data stored in the RFID tag microchip back to the RFID tag reader, e.g., by switching low resistance across the antenna coil, and the capacitor discharges. The change in voltage across the RFID tag antenna generates an RF signal referred to as backscattering. When the signal is received at the RFID tag reader, the reader removes or demodulates the carrier RF signal, and the resulting digital signal can be decoded.
Active RFID tags, in contrast, include a transmitter for sending information to the reader rather than merely reflecting a signal from the reader as the passive RFID tag does. In order to provide power for the signal transmission, active RFID tags include a power source, such as a long-life battery, which provides power to the circuit of the microchip and to the antenna to broadcast a signal to a reader. Semi-passive RFID tags are a hybrid of the two. They include batteries, but they communicate using the same backscatter technique as passive RFID tags, using battery power only to run the circuitry of the microchip, and in some cases an onboard sensor. Semi-passive RFID tags have a longer read range than passive RFID tags because all of the energy gathered from the reader can be reflected back to the reader. Active and semi-passive RFID tags are typically used to track high value goods that need to be scanned over long ranges, and are typically more expensive to produce than passive RFID tags. Passive RFID tags, in contrast, may use ultra-high frequency RF waves, and may have a shorter range such as, e.g., less than 20 feet.
Biological samples are typically stored in containers or vials, and may be kept at conservation temperatures of about −170° C. (−274° F.). These vials may be equipped with RFID tags affixed to the vials using an adhesive for identifying the samples. In many cases, passive RFID tags are used in such applications. Before selecting a sample for use or testing, the RFID tag must be read in order to identify the requested sample. Before they can be read, however, conventional RFID tags must be warmed to a temperature of about −80° C. (−112° F.), which may take upwards of 20 minutes. This may cause the tagged biological sample to reach and sustain higher temperatures than may be desirable to maintain the sample's integrity.
Examples of biological samples which may be stored in this manner may include, for example, samples collected during clinical trials of pharmaceuticals, research samples in labs, samples archived in hospitals, forensic samples from crimes or disasters, samples maintained at the Center for Disease Control (CDC), and samples used for in vitro fertilization.